Let me speculate as to why Baptists historically avoided the term "elder" (though, obviously there are exceptions, the most notable being "Elder Benjamin Randall").
Baptists, as we know, decided that the church's sole locus of authority should not be a ruling board. Of course, ruling boards were called "presbyteries" or "board of elders" or some such back then. Thus, the term "elder" in recent centuries had the connotation of a very powerful individual church leader who, with the help of a few other people, was in the habit of making all the major decisions for a church, without approval of the church membership. Thus, for example, we have the tragedy of Grace Church, Nashville, where the four member elder board dissolved a highly functioning church without any consultation or vote of the congregation.
Since our Baptist forefathers wanted no part of a system of church governance where a board of elders had sole authority over the church, I now speculate that they came to avoid the term "elder" precisely because it had such a negative conotation to them.The same happened with the term "bishop." Baptists exchanged the term "bishop," which connotated an authoritarian semi-Pope, for the more apt term "pastor" which conveys that the leader leads by persuasion, administration, and example, rather than by fiat.
In fact, since in recent history the term "elder" came to connote such a powerful church leader who, with a few others, made all the church decisions unilaterally, we might even be able to say that the term has evolved far beyond its meaning as expressed in the NT documents.
At any rate, since the term "elder" had this negative connotation, Baptists had to replace the term with another term. Of course, the Pastoral epistles portray deacons as church leaders, and so that term was readily available. Consequently, Baptists set up a system of leadership wherein a certain number of church leaders were elected to do pastoral kinds of ministry, without usurping the authority of the congregation. These leaders were just like the NT elders, but they didn't call them "elders" precisely because of the perceived evolution of the meaning of the term. In this light, again, I don't care if you call them deacons, or elders, or Grand PooBahs.
This group of people chosen by the congregation helps the pastor direct the affairs of the church, provides spiritual guidance to the church, helps formulate vision, ministers in various ways, helps hold the pastor accountable to the congregation, and represents the interests of the congregation. They don't however, usurp congregational authority. If an "elder board" operates on this model, then it is a "congregational" model, even if it calls itself an elder board. Essentially, it is Baptistic/congregational.
If, however, the board--whether called Deacons, Elders or Elderberries--has ultimate authority over the congregation, it is a "presbyterian" form of government.
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